Differential tuning mechanism



Oct. 30, 1951 A. H. WULFSBERG DIFFERENTIAL TUNING MECHANISM Filed March 31, 1950 i N 5 & a 3

IN V EN TOR ARTHUR/7. WULFSBERG ,4 TTOPNEY Patented Oct. 30, 1951 signor to Collins Radio Company, Cedar Rapids,

Iowa; a corporationof Iowa- Application-Malena, 1950-;-Serial':No.: 153,178 s Cl'ain'is. (o1. 74:40.6);

This invention relates. iri general .to tuning.

mechanisms, and in particular to a new and novel diifrential tuning device.

It is often desirable .to-make-an adjustment which requires a coarse and a fine change. For example, if a change in positionis tobe a relatively large one it is impractical to" use a'fine adjust ment controliito' move from one position to another, and thus a coarse adjustment is required to.quickly-. move to the vicinity. of the new position; The fine adjustment may then be-usedto find the exact position.

An object of this invention is to provide means for accomplishing differential tuning.

Another object of this invention is to provide a novel arrangement for tuning a longitudinally movable body.

Another object of this invention is to provide an inexpensive and easy to operate differential tuning mechanism.

A feature of this invention is found in the provision for a generally U-shaped bracket which carries a first shaft rotatably supported therein with camming means mounted thereon and with the camming means engageable with slidable bearings mounted within the frame member to move them up and down. A second shaft is rotatably supported in said slide bearings and carries second camming means engageable with a sliding plate. The sliding plate may thus be moved vertically by rotating both of the shafts. The second camming means generally covers the coarse adjustments and the fine adjustments are made by the first camming means.

Further objects, features and advantages of this invention will become apparent from the following description and claims when read in view of the drawings, in which;

Figure l is a perspective view of the diflerential tuner of this invention; and,

Figure 2 is a sectional view taken on the line 2--2 of Figure 1.

Figure 1 illustrates a bracket, designated generally as II), which comprises the base I I and the end portions l2 and I3, respectively. A shaft I4 is rotatably supported adjacent the lower ends of the legs I2 and I3 and carries thereon cams I6 at either end thereof. A rectangular opening I! is formed in the ends I2 and I3 above the shaft I4. the slots I! as shown in Figure-2. The blocks I8 are formed with the recesses I9 for receiving the edges 2| of the end walls. A second shaft 22 is rotatably supported in the block I 8 and second camming means 23 are mounted thereon Slidable blocks I8 are slidably mounted in between theends- I2 and I3.l A plate 24' extends between the .end---walls .l2 and- I3 :andride s in guides 26 formedintheend walls I2 and I3.- A:

plate 24 -hasextending portions 2T at either end thereof .to. be received in therecesses 26.

Springs 28 are attached to the ends 21 ofthe plate 24 by holding means--as,-for-example the pinss29, and-the opposite endcfJthe springs'23 are connected to the end-.walls I 2' and I 3.

Thus-the plate 24 isalways urged downwardly.

with. reference to Figure Downwardly extending portions 3I are attached to the under side of the plate 24 and are engaged by the cams 23. A plurality of rods 32 extend from the plate 24 and terminate in slugs 33 which may be, for example, tuning slugs for variable inductors. As is well known to those skilled in the art, the inductance of a coil of Wire may be varied by adjusting the longitudinal position of a magnetic core relative to the coil.

In operation the shaft 22 may be rotated manually, or by suitable driving means, not shown, and the plate 24 will move up and down in response to the rotation. The cam 23 may have a varying radius and coarse adjustments of the longitudinal position of the slugs 33 may be made by rotating the shaft 22. Rotation of the shaft I4 causes the blocks I8 to move up and down in the opening IT. The cam I6 may have a relatively small change in radius and can be used to make fine adjustments.

As the shaft I4 is turned the cam I6 imparts motion to the blocks I8, which in turn move the cams 23 and the plate 24. The springs 28 bias the plate 24 downwardly with reference to Figure 1 and thus as the cams 23 and I6 are turned in a direction to decrease the radius, the springs will maintain the cammed portions in contact with the cams.

One embodiment of the apparatus built by applicant has a cam I6 with a radius change of 1 s the radius change of cam 23. Thus if the shaft 22 is movable to ten equally spaced positions, the shaft I4 may be used to locate any point between the steps of the cam 23.

It is to be understood, of course, that any number of slugs 33 may be mounted on the plate 24.

Although this invention has been described with respect to a particular embodiment it is not to be so limited as changes and modifications may be made which are within the full intended scope of this invention, as defined by the following claims.

I claim:

1. Means for differentially moving a body comprising a generally U-shaped frame, a first shaft rotatably supported between the legs of said frame, a block slidably supported in each end of said frame, a second shaft rotatably supported in said blocks, a pair of cams on said first shaft engageable with said blocks, a plate slidably mounted on the ends of said frame member, a second pair of cams mounted on the second shaft and engageable with said plate, and flexible means connected to said plate and said frame member, to urge the plate toward said second cams.

2. Mechanism for differentially moving a body comprising, a base member, an upright supporting member at either end of said base member, a plate slidably supported between said support members, a block slidably mounted in a slot formed in each of the support members, a first shaft rotatably supported in said blocks, firstv camming means mounted on said first shaft and engageable with said plate, a second shaft mounted adjacent the lower end of said supports and second camming means carried on said shaft and engageable with said blocks to move them in response to rotation of said second shaft.

3. A system according to claim 1 wherein a plurality of inductive slugs are mounted on said plate to move them therewith.

4. Means for varying the position of a plate comprising, a pair of upright supports formed with guides for receiving said plate, a slot formed in each of said upright supports, a block slidably mounted in the slots formed in said upright supports, a first shaft rotatably supported in said blocks, first camming means carried on said shaft and engageable with said plate, spring biasing means connected between said plate and said upright supports to urge said plate into engagement with said first camming means, a second shaft rotatably supported in said upright supports, and second. camming. means carried on said second shaft and engageable with said slidable blocks.

5. Means for varying the inductance of a slugtuned coil comprising, an upright supporting means, a first shaft rotatably supported in said supporting means, first camming means carried on said first shaft, a block slidably mounted adjacent said first shaft for slidable motion on said 7 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,156,560 Bachman May 2, 1939 2,483,105

Rennick Sept. 27, 1949 

